The Stovebolt Site Forums The Shop Area Engine Shop What engine oil in 1951 chevrolet

Hi guys quick question.

What kind of motor oil do I need to use for a 216 straight 6 engine from 51? The engine has been rebuild but I don't know how many miles ago (probably around 400 miles).

With kind regards,
Thijs

I think I'm going to go with a diesel rated 15W40 with a shot of ZDDP additive, since the diesel oils recently reduced their additive levels. Use to be about 2000 ppm of zinc and now under 1000.

This Shell Rotella 15W40 already has "a shot of ZDDP".

"Our Rotella T4 15W-40 (CK-4) contains about 1200 ppm of zinc and 1100 of phosphous. These are the components of the ZDDP for anti-wear protection. Rotella T4 15W-40 (CK-4) is generally recommended for older flat tappet cam motors.""

Klhansen why diesel rated? Is this not harmful for a petrol engine?

If anything, Diesel rated oil is much better than automotive oil. It's additives allow it to keep the bearings lubricated under the stress of compression ratios of anywhere from 16:1 up to 22:1 or more. Most automotive engines have compression ratios of less than 10:1, and stovebolt engines struggle to get much motre than 8:1.
Jerry

Nearly all Diesel rated oils are also rated for gasoline (petrol) engines, but like Jerry said, diesel oils are more robust.

Can you find oil for diesels? Our Walmarts have empty shelves right now.

I buy my 15W40 in 5 gallon pails from Tractor Supply. Everything at our place runs it- - - -cars, trucks, tractors, lawn mowers, pumps, generators, even my Harley EVO.
Jerry

Lots of British car guys use Valvoline VR1 in the Triumph/MG/etc inline 4/6 with flat tappets like the GM motors. 20/50 with lots of zinc. Also Brad Penn makes a nice product. But yeah Rotella is great and cheap. KTM factory race mechanics tend to run Rotella in their racer's 4stroke bikes because they believe it's better (and for sure cheaper) than the recommended Motul 4T. And those motors take a proper beating.

We have a jerrycan of 20W50 laying around which is specifically made for classic cars. We use it all the time for our MG B (inline 4) and it always runs great. But that's why I asked what kind of oil I should use for our truck, because I don't know if 20W50 is a good oil for it. Getting the oil is no issue, because we have a couple of jerrycans laying around with 15W40 but I don't know how much zinc is in it.

15W40 has a little better cold flow characteristics than 20-50. Otherwise either one should work well. If you're starting the engine in sub-freezing temps, it will crank a little faster and get pressurized oil to the end of the lubrication circuit sooner with 15-40.
Jerry

In the winter our truck is stored in a heated garage. We never drive it when it is under 5 °C (41 °F). So it doesn't need the cold flow characteristics of 15w40. So I guess 20w50 is fine?

Sounds good- - - -since "multi weight" oils actually stay at the physical thickness of the low specification regardless of temperature, just stay away from extremely low viscosity oils like 5W-30, etc. The "high" number simply indicates that the oil lubricates like a thicker one when it's hot. The thin ones don't provide enough cushioning for parts with relatively wide oil clearances like stovebolt engines have.
Jerry

I’m running 10-W30 with a dose of ZDDP.